The present invention relates to an electronic control camera in which, when an electronic flash is used, the exposure data are automatically set.
In recently developed electronic control cameras, an electronic flash is often combined with a camera. In such a camera, photographing operations can be carried out electrically with the electronic flash, or the operation of the electronic flash automatically controlled by the camera, or the electronic flash is built into the camera. Furthermore, an exclusive electronic flash can be provided so that the camera can be used in various manners. Thus, a variety of electronic flashes differing electrically and mechanically have been developed for use with electronic control cameras.
The amount of light emitted by such an electronic flash is indicated by a value GN (guide number). With the shutter speed set to a certain value or higher, the amount of light emitted is, in general, determined by the product of the aperture value and the illumination distance (or photographing distance). Therefore, if, when the photographing distance is set, the aperture value is determined mechanically in association with the distance set then the correct amount of light emission can be obtained.
In a photographing operation, essential factors for determining exposure data correctly are film sensitivity, shutter speed, aperture value and the object's luminance. In a photographing operation with an electronic flash, it is necessary to add two more factors, electronic flash guide number and photographing distance (distance to the object), to the above-described four factors, and in this case it is especially desirable that the exposure data be selected correctly.